Anti-knock index

Also known as: AKI, DON, R+M/2

The anti-knock index is a measure of gasoline octane that attempts to capture both the measure of research octane and motor octane in one number.

It is most commonly used in the US and Canada, where it is the primary indicator of octane provided to consumers at the pump.

In most other markets, road octane alone is the primary indicator of octane quality.

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